Commutator motor with switching arrangement for the rotor windings



April 20, 1926.

c. Lo1"r COMMUTA'I'OR MOTOR WITH SWITCHING ARRANGEMENT FOR THE ROTORWINDINGS FiledMarch 11. 1926 HTT'QRN'EYS.

Patented Apr. 20, 1926.

PATENT OFFICE."

UNITED STATES CARL mm, or ZURICH, swTTzEnLAnD.

Application filed March 11, 1926. Serial No. 94,030.

To all whom it may come m:

Be it known that I, CARL LOTT, a citizen of the Republic of Switzerland,residing at Zurich, in the Republic of Switzerland, have invented newand useful Improvements in Oommutator Motors with Switching Arrangementsfor the Rotor WVindings, for which applications have been filed inSwitzerland, November 7, 1924; Germany, September 9, 1925; GreatBritain, September 15, 1925; Austria, September 25, 1925;Czechoslovakian Republic, October 17, 1925; France, October 17 1925;Belgium, October 17, 1925; Italy, November-5, 1925; Spain, November 6,1925; Sweden, November 6, 1925; and of which the following is aspecification.

It. is common to providethe rotor of a motor with two windings and twocommutators in order to use one and the same rotor, for instance for twodifferent tensions. These arrangements cannot be used on the grounds ofeconomy since the wear and power requirements of the two commutator-sare too great and in addition the machine is too long. The purpose ofthe present invention is to overcome these disadvantages. For thispurpose the machine is provided with a switch arrangement in order toenable the rotor to be set for the tension in question, the connectionbetween the commutator and rotor winding being so made by means of theswitch arrangement that the coils are either connected in series orgroupwise in parallel.

An embodiment of the invention in a lo tor with a lap winding is shownby way of example in the accompanying drawings,

Figures 1 to 3 show three dilierent connections or the rotor winding.

Figure 4 is an elevation of the switch arrangement seen from thecommutator side.

Figure 5 is an axial section of Figure a.

In Figures 4 and 5, 1 is a ring of insulating material on which aresecured contact springs 2, which bear on the margin 3 of the commutator4L and make electric contact each with one segment thereof. The ring isprovided with as many contact springs as the commutator has segments. Aconnecting wire 11 is soldered to each contact spring which it connectswith the finishing end of one coil or the rotor winding. The commencingend of each rotor coil is connected with a collector segment through aconductor 14. The ring 1 is rotatably held on the margin 3 of thecommutator 4; by the contact springs 2 and the plate 5 which are locatedat the opposite faces 01 the ring 1. The plate 5 is secured to the'ring1 by a screw 10. The plate 5 acts at the same time as an indicator ofthe setting of the ring in relation to the disc 6, having an indicatingopening 9through which. setting numbers 15 on the disc are seen. 7 and 8are stops to limit the rotation. of the ring. The contact springs aresecured to the ring by rivets 12. 1

Figure 1 shows diagrammatically the connection at setting 1 of theswitch arrange- 7 ment, in which the connections are such that thefinishing end of each coil is electrically connected with thecommencement of the next,-all the coils thusbeing connected in series inthe usual way. If now the ring 1 is turned to position 2, thus movingthe ends of the contact springs bearing on the commutator one segmentfurther on, the finishing ends of the coils are connected no lower withthe commencement 01 the next, 0' but with the next but one coil (Figure2). There is formed in this way a winding with two groups, of which thecoils are connected among themselves in series, but the groupsthemselves in parallel. If the switch ar- 35 rangement is turned toposition 3, the contact springs being moved therefore over two segments,three parallel connected groups of coils in series are formed The brushthicknesses are. so designed corresponding to this third position, thatthe current can flow si multaneously through all three, the crosssection ofthe winding being in this way increased two-fold for position2 and threefold for position 3, the ohmic resistance decreased two orthree fold thus enabling the use of a tension decreased approximately inproportion.

The number of commutator segments is advantageously so designed that itis divisible without remainder by the ordinal numbers of all thedifferent connections; that it is divisible when for examplea series offour different connections are to be possible, by 2, 3 or 1 withoutremainder, for example 1 therefore, 1.2, 2 k, 36, 48 and so forth.

Advantageously the stator of a machine with a rotor switchingarrangement of this kind is provided with a tapped winding in order tosuit the stator field to the rotor field. 11

Having now particularly described and ascertained the nature of my saidinvention.

and in what manner the same is to be performed, I declare that what Iclaim is 1. A. commutator motor, comprising, in combination, acommutator with a projecting margin, a rotatable ring surounding themargin, a number of contacts, equal to the number of the commutatorsegments, secured to the ring and bearing on the margin, each of thesecontacts being electrically connected to one end of a rotor coil, theother end of which is electrically connected to arommutator segment.

2. A comn utator motor, comprising, in combination, a commutator with aprojecting margin, a rotatable ring surrounding the margin, a number ofcontacts, equal to the number of the commutator scgn'ients, secured tothe ring and bearing on the margin, each of these contacts beingelectrically connected to one end of a rotor coil, the other end ofwhich is electrically connected to a commutater segment, and a disc onwhich the rotatable ring is held by means of a plate secured to thering.

8. A commutator motor, comprising, in combination, a commutator with aprojecting margin, a rotatable ring surrounding the margin, a number ofcontacts, equal to the number of the commutator segments, secured to thering and bearing on the margin, and a disc on which the rotatable ringis held by means of a plate secured to the ring, and

,forming an indicator, which shows the setting ior the time being of theconnections.

l. A commutator motor, comprising, in con'ibination, a commutator, arotatable ring surrounding the commutator, a number of contacts securedto the ring and bearing on the commutator, each oi these contacts beingelectrically connected to one end of a rotor coil, the other end ofwhich is electrically connected to a commutator segment. 7,

5. A commutator motor, comprising, in combination, a commutator,a'rotatable ring surrounding the commutator, a number of contacts, equalto the number of the commutator segments, secured to the ring andbearing on the commutator, each of these contacts being electricallyconnected to one end of a rotor coil, the other, end of which iselectrically connected to a commutator segment.

In testin'iony whereof I have signed my name to this specification.

CARL LOTT.

